In the field of industrial materials such as automobile parts and electric appliances, conventional methods applied for decoration of moldings for indoor and outdoor uses include a process in which a decorative layer composed of an adhesion layer, coloring layer, and protective layer is formed on top of a molding by spraying paint to produce these layers. This process, however, requires many steps and costs as baking is necessary for each layer that constitutes the decorative layer. In addition, it has the problem of an increased release of volatile organic compounds and CO2 that can cause a large environmental load. This problem has been solved in recent years by new film decoration methods such as vacuum molding and air-pressure molding that can decorate moldings of a three-dimensional shape.
Moldings to be decorated, on the other hand, may be of different materials such as metals and resins, of which resins have been widely used as material of moldings from the viewpoint of light weight, rustproofing properties, and high moldability. In the field of industrial materials such as automobile parts and electric appliances, in particular, the consumption of polyolefin based resins, which are chemical resistant, water resistant, and heat resistant, though low-priced, has been increasing sharply. Polyolefin based resins, however, have the problem of lacking functional groups that can contribute to reactions, and they are poor in adhesiveness because of being crystalline.
As a method to solve this problem, formation of a primer layer on polyolefin based resin products has been proposed (Japanese Unexamined Patent Publication (Kokai) No. 2004-947). It has also been proposed to provide a base coat film layer that can serve also as a primer (Japanese Unexamined Patent Publication (Kokai) No. 2006-37072). On the other hand, there is another proposal of a film decoration method that takes into account the stretchability of coat films.
With the method proposed in JP '947, however, adhesion between the primer coat layer and the base coat layer decreases. With the method proposed in JP '072, it is impossible to maintain sufficient adhesion between the polyolefin based resin and the coat film layer after water resistance test.
The methods proposed in JP '947 and JP '072 which assume the use of spray coating, furthermore, cannot produce a coat film with high stretchability and cannot serve at all as a decoration method for a film that requires high moldability.
With the methods proposed in JP '886 and JP '262 which take into account stretchability of coating films, on the other hand, sufficient adhesion cannot be achieved between the primer coating layer and the base coating layer when film decoration is performed on a polyolefin resin product.
Thus, it could be helpful to provide a laminate film high in adhesiveness to polyolefin based resins, high in moldability, and suitable for decorative molding.